This invention relates to a slipper spring for linearly and radially resiliently retaining a friction pad within first and second grooves in anchor of a disc brake.
Anchors for disc brakes are often manufactured through a casting process wherein molten metal is poured into a die to define a broad general shape and later surfaces involved in the functional operation of the anchor such as pin bores, guide surfaces, alignment surfaces and etc, are finished to a smooth surface. The guide surfaces on the anchor include grooves that receive ears on backing plates that carry friction pads and surfaces that are mated with surfaces on a vehicle to align the grooves in a manner to provide for perpendicular engagement of the friction pads with a rotor. This type anchor functions in a disc brake in an adequate manner, however, after an extended period of time grooves. This wear has an effect on a smooth movement of the backing plate toward the rotor for an individual brake and may be sensed by operator as a non-synchronized brake application. The wear can be expected since the anchor and backing plate are made of different metals that have different coefficients of friction and coefficient of thermal expansion. With respect to thermal expansion a sufficient tolerance is always required between an ear on the backing plate and groove in the anchor or binding will occur under certain thermal operating conditions. As a consequence, a minimum manufacturing tolerance is essential between the components for operating under a wide range of thermal conditions. In order to reduce or control the wear between components it is common to line the groove with a cap having an equivalent or lower coefficient of friction than the backing plate. Unfortunately, this change in structural components also increased the minimum tolerances necessary to avoid thermal binding and as a result a spring was expediently added to resiliently urge the ear into engagement with the cap to attenuate the development of noise between the components when a vehicle travels on a rough roadway.
A primary object of the present invention is to provide an anchor plate for a disc brake with integral slipper springs that are located in grooves to resiliently axially align a backing plate retained between the grooves with a rotor and resiliently radially urge ears on the backing plate into engagement with a corresponding side wall of the grooves to absorb and dampen movement caused when a vehicle travels on a rough road.
According to this invention, then anchor member which is fixed to a support member on a vehicle has first and second grooves that correspondingly receive first and second ears on a backing plate. A first slipper spring is secured to the anchor and located between the first groove and the first ear and a second slipper spring is secured to the anchor and located between the second groove and the second ear. The first and second ears engage the corresponding first and second slipper springs to hold and align a friction surface on a friction pad attached to the backing plate with a rotor. The first and second ears correspondingly sliding in first and second slipper springs in response to an input force being applied to move the backing plate toward the rotor and the friction surface into engagement with the rotor to effect a brake application. Each of the first and second slipper springs is characterized by a base having parallel first and second side walls that extends therefrom. The first wall has a lip thereon that engages the anchor to position the base adjacent the bottom of one of the first and second groove. The second wall has an arm that extends from a point along a plane that forms an angle of less than 90 degrees with respect to the base and the wall. The arm tangentially engages the backing plate to resiliently urge the ear away from base groove to define a first gap between the ear and the base and to resiliently urge the ear into engagement with the first wall to define a second gap between the ear and the second wall. The first and second gaps function to reduce the possibility of binding that may occur as a result of differences in thermal expansion of the anchor and backing plate.
An advantage of this disc brake resides in a smooth actuation during a brake application resulting from a resiliently axially, radially and tangentially retained backing plate.
A still further advantage of this disc brake resides in a quite structure wherein noise caused by vibration is absorbed by a radial component of a tangential spring force provided by a cantilever arm that extends from a slipper liner for an aligning groove of an anchor.